Does anyone know where a guy can get a normally closed key switch to use with a high tension mag?
Don't know if this is what you want.
The Napa electrical parts catalog lists key switches with specs. Some will be found suitable for mag equipped engines. They list a lot of stuff for power equipment with mag ignition.
Tom I just keep my eyes peeled on eBay and search "Bosch magneto switch" there's almost always one for sale on there. Just like what Stephen linked.
This is from just last month, but maybe one of the switches with the ground terminal on the back would work;
Layden Butler had one or two bosch switches for sale recently.
older farmall tractors have a kill switch that grounds the mag